Why doesn't ctrl+left and ctrl+right work by default in alacritty?

Question

As in the title.

I run vim in xterm and ctrl-left and ctrl-right does work (skips over one word in the text by default -- this is likely the intended behavior, also because it works the same way in gvim), while in alacritty it does not work (glitchy behavior, as described below in a linked question).

I'm using Vim 9.0 with patches 1-910 included.

Some investigations:

• If I understood correctly, when the user presses some key on the keyboard, first the terminal process it, send some key codes to vim, then vim read it.
• :help termcap → my vim version has +terminfo, so the data of the key codes of the keys will be read from terminfo database.
• pressing ctrl-right sends ^[[1;5C in both terminals.
• looking at the source code of ncurses, ctrl-right should be kRIT5.
• oddly enough man terminfo does not have kRIT5 cap-name, but does have kRIT which corresponds to "shifted right-arrow key" or %i termcap code. Maybe kRIT5 is some extension?
• identifying infocmp unfortunately does not print out kRIT5, but tput kRIT5|xxd correctly prints ^[[1;5C for both xterm and alacritty. -- thus the information in the terminfo database is correct.
• :set termcap will print out all the key codes according to :help terminal-options -- oddly enough there's no entry correspond to kRIT5, yet it works in xterm anyway.

Any idea what's going on?

Some related questions:

• terminal - Vim does not react to Ctrl key combinations on alacritty - Vi and Vim Stack Exchange -- have no satisfactory answer. My vim version already greater than 8.2.
• How can I see what keys vim thinks I'm hitting? - Stack Overflow nothing useful.
• key bindings - What exactly Ctrl + Shift + Right arrow does? How can I remap it or find help on this key combination? - Vi and Vim Stack Exchange nothing useful. (it describes the "glitchy" behavior of ctrl+shift+right)
• vimrc - Control - Arrow to Skip Over Text - Vi and Vim Stack Exchange nothing useful (it doesn't explain why the terminfo entries are not read by default in alacritty, but does (?) in xterm)

---

Additional info:

$ infocmp alacritty
#       Reconstructed via infocmp from file: /usr/share/terminfo/a/alacritty
alacritty|alacritty terminal emulator,
        am, bce, ccc, hs, mc5i, mir, msgr, npc, xenl,
        colors#0x100, cols#80, it#8, lines#24, pairs#0x10000,
        acsc=``aaffggiijjkkllmmnnooppqqrrssttuuvvwwxxyyzz{{||}}~~,
        bel=^G, blink=\E[5m, bold=\E[1m, cbt=\E[Z, civis=\E[?25l,
        clear=\E[H\E[2J, cnorm=\E[?12l\E[?25h, cr=\r,
        csr=\E[%i%p1%d;%p2%dr, cub=\E[%p1%dD, cub1=^H,
        cud=\E[%p1%dB, cud1=\n, cuf=\E[%p1%dC, cuf1=\E[C,
        cup=\E[%i%p1%d;%p2%dH, cuu=\E[%p1%dA, cuu1=\E[A,
        cvvis=\E[?12;25h, dch=\E[%p1%dP, dch1=\E[P, dim=\E[2m,
        dl=\E[%p1%dM, dl1=\E[M, dsl=\E]2;\007, ech=\E[%p1%dX,
        ed=\E[J, el=\E[K, el1=\E[1K, flash=\E[?5h$<100/>\E[?5l,
        fsl=^G, home=\E[H, hpa=\E[%i%p1%dG, ht=^I, hts=\EH,
        ich=\E[%p1%d@, il=\E[%p1%dL, il1=\E[L, ind=\n,
        indn=\E[%p1%dS,
        initc=\E]4;%p1%d;rgb:%p2%{255}%*%{1000}%/%2.2X/%p3%{255}%*%{1000}%/%2.2X/%p4%{255}%*%{1000}%
/%2.2X\E\\,
        invis=\E[8m, is2=\E[!p\E[?3;4l\E[4l\E>, kDC=\E[3;2~,
        kEND=\E[1;2F, kHOM=\E[1;2H, kIC=\E[2;2~, kLFT=\E[1;2D,
        kNXT=\E[6;2~, kPRV=\E[5;2~, kRIT=\E[1;2C, kb2=\EOE, kbs=^?,
        kcbt=\E[Z, kcub1=\EOD, kcud1=\EOB, kcuf1=\EOC, kcuu1=\EOA,
        kdch1=\E[3~, kend=\EOF, kent=\EOM, kf1=\EOP, kf10=\E[21~,
        kf11=\E[23~, kf12=\E[24~, kf13=\E[1;2P, kf14=\E[1;2Q,
        kf15=\E[1;2R, kf16=\E[1;2S, kf17=\E[15;2~, kf18=\E[17;2~,
        kf19=\E[18;2~, kf2=\EOQ, kf20=\E[19;2~, kf21=\E[20;2~,
        kf22=\E[21;2~, kf23=\E[23;2~, kf24=\E[24;2~,
        kf25=\E[1;5P, kf26=\E[1;5Q, kf27=\E[1;5R, kf28=\E[1;5S,
        kf29=\E[15;5~, kf3=\EOR, kf30=\E[17;5~, kf31=\E[18;5~,
        kf32=\E[19;5~, kf33=\E[20;5~, kf34=\E[21;5~,
        kf35=\E[23;5~, kf36=\E[24;5~, kf37=\E[1;6P, kf38=\E[1;6Q,
        kf39=\E[1;6R, kf4=\EOS, kf40=\E[1;6S, kf41=\E[15;6~,
        kf42=\E[17;6~, kf43=\E[18;6~, kf44=\E[19;6~,
        kf45=\E[20;6~, kf46=\E[21;6~, kf47=\E[23;6~,
        kf48=\E[24;6~, kf49=\E[1;3P, kf5=\E[15~, kf50=\E[1;3Q,
        kf51=\E[1;3R, kf52=\E[1;3S, kf53=\E[15;3~, kf54=\E[17;3~,
        kf55=\E[18;3~, kf56=\E[19;3~, kf57=\E[20;3~,
        kf58=\E[21;3~, kf59=\E[23;3~, kf6=\E[17~, kf60=\E[24;3~,
        kf61=\E[1;4P, kf62=\E[1;4Q, kf63=\E[1;4R, kf7=\E[18~,
        kf8=\E[19~, kf9=\E[20~, khome=\EOH, kich1=\E[2~,
        kind=\E[1;2B, kmous=\E[<, knp=\E[6~, kpp=\E[5~,
        kri=\E[1;2A, mc0=\E[i, mc4=\E[4i, mc5=\E[5i, meml=\El,
        memu=\Em, oc=\E]104\007, op=\E[39;49m, rc=\E8,
        rep=%p1%c\E[%p2%{1}%-%db, rev=\E[7m, ri=\EM,
        rin=\E[%p1%dT, ritm=\E[23m, rmacs=\E(B, rmam=\E[?7l,
        rmcup=\E[?1049l\E[23;0;0t, rmir=\E[4l, rmkx=\E[?1l\E>,
        rmm=\E[?1034l, rmso=\E[27m, rmul=\E[24m,
        rs1=\Ec\E]104\007, rs2=\E[!p\E[?3;4l\E[4l\E>, sc=\E7,
        setab=\E[%?%p1%{8}%<%t4%p1%d%e%p1%{16}%<%t10%p1%{8}%-%d%e48;5;%p1%d%;m,
        setaf=\E[%?%p1%{8}%<%t3%p1%d%e%p1%{16}%<%t9%p1%{8}%-%d%e38;5;%p1%d%;m,
        sgr=%?%p9%t\E(0%e\E(B%;\E[0%?%p6%t;1%;%?%p5%t;2%;%?%p2%t;4%;%?%p1%p3%|%t;7%;%?%p4%t;5%;%?%p7
%t;8%;m,
        sgr0=\E(B\E[m, sitm=\E[3m, smacs=\E(0, smam=\E[?7h,
        smcup=\E[?1049h\E[22;0;0t, smir=\E[4h, smkx=\E[?1h\E=,
        smm=\E[?1034h, smso=\E[7m, smul=\E[4m, tbc=\E[3g,
        tsl=\E]2;, u6=\E[%i%d;%dR, u7=\E[6n,
        u8=\E[?%[;0123456789]c, u9=\E[c, vpa=\E[%i%p1%dd,

As evidenced by tput kRIT5 command output above this should be correct, although kRIT5 itself isn't included in infocmp even though the terminfo file seemingly does contain it.

Alacritty version:

alacritty 0.11.0 (8dbaa0bb)

I'm not using tmux, only vim inside alacritty.