Having just moved house the previous owners had some very I’ve eager dogs . There’s some scratches up the patio doors .
Can these be polished out or is it new glass ?
Another how long is a piece of string question!
The answer of course like everything else is, it all depends!
How large is the pane of glass? Is it double glazed? uPVC or wood frame ? When was it installed ?
If it's in any way reasonably recent it is a legal requirement that all glass fitted to doors is toughened, and you should be able to confirm this by an etching in the glass itself, with the BS kite mark. If it is UPVC replacement is simple, but my local glass supplier is running on a 3 week lead time. The cost will be dependent on the size and this is the question only you can answer. Double glazed units fail and yours will too at some point but again it's all down to your decision. There are instructions on how to polish scratches out of toughened glass on You tube should you shoose to go that way.