ZSH script exits even though ERR_EXIT is off - while-loop

Question

I have this pipeline in my shell script. It's meant to prompt the user to select PulseAudio sources to record with ffmpeg, but to the best of my knowledge, that doesn't matter for this specific issue.
integer num_sources=0
pactl list short sources \
| while IFS= read -r line; do if [[ "$line" =~ '^([[:digit:]]+)\s+(\S+)' ]]; then
echo "#$match[1]: $match[2]"
fi; done \
| (fzf -m --prompt='Select audio source: ' || true) \
| while IFS= read -r src_line; do if [[ "$src_line" =~ '^#([[:digit:]]+)' ]]; then
local pulsesrc="$match[1]"
(( num_sources++ ))
ffpulseopts+=(
-f pulse
-i "$pulsesrc"
)
fi; done
My issue is that, if I remove the || true from the fzf invocation, leaving fzf by means of pressing Escape, which causes a non-zero exit code, will cause the entire script to terminate. I don't understand why this happens, even though neither the ERR_EXIT nor the ERR_RETURN options are set. PIPE_FAIL is not set either, though I'm not sure how it would come into play here.
λ unsetopt | egrep '^(err|pipe)'
errexit
errreturn
pipefail
I have verified this issue with shorter examples as well; the following snippet will not print foo if you exit fzf with Escape. This doesn't happen when fzf is replaced with false, so I was able to trace the issue back to the exit code, which is 130 (indicating SIGINT) when pressing Escape.
λ (echo a; echo b; echo c) | fzf | while IFS= read -r line; do echo $line; done; echo foo
λ (echo a; echo b; echo c) | false | while IFS= read -r line; do echo $line; done; echo foo
foo
λ (echo a; echo b; echo c) | (exit 130) | while IFS= read -r line; do echo $line; done; echo foo
However, if you remove the loop, it will print as expected.
λ (echo a; echo b; echo c) | (exit 130); echo foo
foo
Even when you add other parts to the pipeline, it will still continue to print foo properly
λ (echo a; echo b; echo c) | (exit 130) | false; echo foo
foo
λ (echo a; echo b; echo c) | (exit 130) | true; echo foo
foo
After some fiddling, I found out that it's not just the loop either. It only happens when a middle part of the pipe exits with SIGINT AND the loop is the last part of the pipeline.
λ (exit 130) | while IFS= read -r line; do echo $line; done; echo foo
foo
λ false | (exit 130) | while IFS= read -r line; do echo $line; done; echo foo
λ true | (exit 130) | while IFS= read -r line; do echo $line; done; echo foo
λ false | (exit 130) | while IFS= read -r line; do echo $line; done | false; echo foo
foo
λ true | (exit 130) | while IFS= read -r line; do echo $line; done | false; echo foo
foo
λ false | (exit 130) | false; echo foo
foo
I'm stumped here, and don't really know where to go without a hack like || true (|| false works as well as it turns the SIGINT exit code into a "regular" error exit code).
Edit: Upon request, here is the output of setopt.
λ setopt
alwaystoend
autocd
autopushd
completeinword
extendedglob
extendedhistory
noflowcontrol
histexpiredupsfirst
histignoredups
histignorespace
histverify
incappendhistory
interactive
interactivecomments
kshglob
longlistjobs
monitor
promptsubst
pushdignoredups
pushdminus
sharehistory
shinstdin
zle
Edit 2: Some system context upon request
I am on an up-to-date (as of May 2nd, 2020, 19:04) Arch Linux, with ZSH 5.8.