Using `everydisplay` crashes split environment

I use TeX Live 2020 on Debian Testing; version of amsmath is 2.17e. I have noticed that I get the error

Package amsmath Error: begin{split} won’t work here. end{split}

whenever there is an everydisplay command and try to use the split env. within any math environment, whether display math (any delimiter), equation, eqnarray, and their starred versions. Here’s a MnWE:

documentclass{article}

usepackage{amsmath}
usepackage{color}

everydisplay{color{blue}}

letequationgather
letendequationendgather

begin{document}

Line.
begin{equation}
begin{split}
a & = b
c & = d
end{split}
end{equation}

end{document}

I tried using the solution here by modifying equation using let as seen above, but it doesn’t work.

Is this some sort of bug? Should I report this somewhere? Is it just me? The only reference to this error in the amsmath doc. is the description of split ("it is not standalone" etc).