It's not a problem related to laser because in that case the contents from CD-ROM would either be unreadable at all or the disc would be spinning strangely etc.
As you can see on the screen capture, there's a difference of 16 characters between the corrupted characters displayed on screen and their expected value. (Example : W-16 = G, u-16 = e, q-16 = a)
So I suspect something wrong happening on D4 pins of your cartridge : if it is returning random signals on the data bus at random timings then the read result from CD-ROM is likely to be corrupted because cartridge and CD Block share the same data bus.
-> Please try to cleanup the connector of your cartridge, and to re-seat it in your Saturn. If needed, please also use the secret technic of lifting the cartridge by around 0.5mm or 1mm after inserting it in your Saturn.
(Please insert/remove your cartridge when Saturn is turned off. Doing that when Saturn is turned on may damage it)