Finally I bought a nice and firm rubber mat after using soft puzzle mats until now. Compared to cheap mats this was a bit expensive but I'm very satisfied with the quality. I decided to pay a bit more and to not choose the cheapest rubber mat I find online because not all rubber mats are made for indoor usage. Some smell strong or the rubber granules will spread after some time because it's made for construction and not for working out on it indoors.
For this 8mm thick, high quality (made in germany) rubber mat I paid 39€ per m² (4mm is half the price). It only covers the area under and around my power rack and not the whole floor. That's enough though and it's not a super huge area so it was within my budget. Similar rubber mats can cost 50€ or more so I think the price is still high but it's alright for the quality. Also the prices are rising in general because of the inflation so yeah. Tbh the cheap puzzle gym mats I bought 2 years ago cost double the price right now (not worth it).
Most gym mats are black which looks nice but I got this pattern that looks kinda cool I think:
Like I said this rubber mat is 8mm thick and firm. I thought that's maybe not enough thickness but it's really enough for putting it on top of a flat surface (in my case wooden floor) under your power rack. I read that maybe horse stall mats and other rubber mats will have a strong smell and because my home gym is literally in the room next to my bedroom I decided to buy a mat that won't smell. This mat has zero smell (maybe a light rubber smell if you directly sniff it but there is no bad or toxic smell in the air). If you have a garage maybe horse stall mats will work for you because they're often cheaper and rubber smell won't be a problem there.
Pictures from my home gym with this mat (pattern looks way nicer in real life):
This was the continuation of my other gym floor post: Click here.