Take Firefox’s 1542044, where the dark mode theme colors aren’t exposed when they should. The patch has been up for 4 years.
Or, take this, which is part of a series that added Doxygen parsing to clangd, a language server. It was left unreviewed until late 2022, the patcher went in conversation with the reviewer, but then met radio silence again, long enough to the point where the patch-reviewing service shut down. Clangd currently has only 44 open PRs to review, though it uses the same issue tracker as llvm for some reason.
Aren’t we paying them to do all this?
I could be wrong, but I’m pretty sure a lot of open source software is volunteer based and unpaid.
There might be cases where orgs will lend developers to work on a project, but with the org’s interests in mind, so if the patch isn’t in their interest, then those devs won’t look at it.