Strange mouse X pointer

[MR ZenWiz]

I run Xubuntu 22.04, fully updated.

I found recently that I don't care so much for the default mouse
cursors because I find them difficult to see.

I changed from the DMZ White theme to DMZ black, then Adwaita, the
latter two of which have white outlined black cursor symbols. That
much is fine.

However, I noticed that sometimes the cursor goes into a X shape, and
it seems to stick across numerous window and workspace boundaries -
but not consistently.

First of all, I don't like the X where I expect an arrow. Second, it
doesn't appear to have a clearly defined switch point I can identify.
(I.e., how to get it to go back to the arrow...)

Can anyone tell me a) why it does that in the first place and b) how
to get it to stop?

I've temporarily reset to the default theme, which doesn't do any of
that, but I really like the white-outlined black images - they're
easier for me to see.

?????

Mark