You have the one with the S-Pen ?
I have used this for a couple weeks... I have a couple of marks but these are on the screen protector. You know you have a screen protector on the display ? When the phone was sold there was a first layer which was a protective transport layer...then a screen protector which is a thicker material... and then the display.
The display is gorilla glass victus to 7H standard... so I very much doubt a plastic cover will cause damage to the screen. I would check first that it isn't just the protector.
I would also expect the screen protector to get marks from time to time... you can always replace this...
The past few releases of Galaxy phone have been supplied with a free screen protector, although prior to S10 there never was one. Personally I think this is a nice touch by Samsung and not a cost saving and it has always been a film type. Other than a transport protector that you remove before usage, you don't get a free screen protector with any other manufacturer phone as far as I am aware. So this is a nice touch...
If preferred, you could remove it, buy a better quality one and replace it. or many people prefer the touch of real glass, so go with the risk. You might get some micro scratches over time, but this is 7H hardness glass, so should not scratch apart from in the case of severe scratches.
I bought this clearview cover, as it gives some extra protection against drops and hope it will cover the screen. Also I made the choice to buy the 2 year Samsung insurance this time around on such an expensive piece of kit, and whilst it was cheaper (£127 instead of £159). A little extra piece of mind in case of drop damage.
If choosing to replace the protector then I would recommend the dome glass if you want best protection, although this comes at a high cost of around £50. ! Most of the others are pretty rubbish to be honest, unless you just want a film for scratch reasons rather than full protection. Also some are not very compatible with touch fingerprints, so choose wisely.