Lots of GLib-CRITICAL's written in ~/.xsession-errors

I am used to have some warnings/errors at ~/.xsession-errors.

However, a fact raised my attention, the file is being populated with tons of

(xfwm4:20982): GLib-CRITICAL **: 20:22:14.195: g_hash_table_lookup: assertion 'hash_table != NULL' failed

Moreover, I noticed that each time I change windows, another line like the previous one is written.

I did some tests and figured out that this happens if I use the combination picom-12.5-1 + xfwm4-4.20. But if I use the native compositor of xfwm4-4.20, the errors are not thrown. Furthermore, the combination picom-12.5-1 + xfwm4-4.18 also does not throw the errors.

So I suspect something has changed in the transition xfwm4-4.18 -> xfwm4-4.20.