no, it traces back to the same thing pretty much, but in modern Polish it's indistinguishable from ż (ž?) I assume that long time ago it went like this r' -> ř -> řż -> ż, which effectively removed the foundational r-ness of the thing.

Off the top of my head, the Polish language has lost the phonetic distinction between

rz and ż -> ż,

h and ch -> ch,

u and ó (flat u vs long o) -> u

In some regional dialects near southern/eastern borders you could still find some of these distinctions, but in modern Polish it's gone.

at a glance shit looks unnecessarily confusing especially for non-slavic foreigners, but once you look more into it explains many things and helps greatly with writing of related words, declination and conjugation, eg where grammar mandates sound substitution (assuming you are Czech you are probably aware of this effect already) For example there are clusters of sounds that often change one into another.

g/h/ż are one such cluster of closely related sounds

noga (leg, noun) vs nożny (adjective)

drugi (second) vs druh (friend, companion) drużba (guy helping the newlyweds with wedding)

Sapieha (noble name of Ukrainian origin) vs Sapieżanka (daughter of Sapieha)

rz/r:

drzewo (tree) vs drewno (wood)

ch/sz is another:

mucha (fly) -> muszka (diminutive)

ó/o/e is another:

bóg (god) vs bożek (lesser god)

pióro (feather) vs pierzyna (bed cover stuffed with feathers)

It also helps seeing similarities between Slavic languages, as this stuff preserves a ton of the common roots. Any Slav seeing 'góra' will know what's up, not so much with phonetically equivalent 'gura'.