Can an OS iso (or software) downloaded in an unsafe environment be still safe for use?

I downloaded some os iso to be burned on a DVD and let's say that my connection was not safe enough and/or my burner application had a malware, tl;dr I downloaded and burned the iso to DVD in a NOT safe environment. Following this guide https://unix.stackexchange.com/questions/373123/how-to-checksum-a-cd-dvd-to-verify-integrity-of-my-debian-installation I checked the DVD burned on a different safe machine and the CRC check is identical to the one provided from the distribution website. Is the DVD burned considered to be safe ? Can other hidden sectors or metadata not being part in the crc process be used to dispatch malware or can I be 100% sure that the DVD content is safe for setup a new machine ?