it is a bit of a mucking fuddle…
ISTR there was a indication that it had been made clear to external border controls that there was no requirement to stamp passports of TCN residents in the Schengen area but that (in some cases) French border control personnel at ports of entry (air, sea and road) were stamping them nonetheless and that it would all resolve itself when ETIAS became active.
That has now been delayed of course so the muddle will likely as not continue.
How that impacts internal travel within Schengen remains unclear except so far perhaps in that, if in the unlikely event they are challenged to do so, a French resident TCN with a WARP carte may be unable to justify an extended period of absence from their host State (differing absence rules applying for 5 year and 10 year WARP cartes).
I’m sure these eventualities may be prescribed somewhere but I’ve not researched it nor found a reference which explains it further.