I'm thinking it looks like some mechanical damage (leaves got torn and/or broken by banging against something) along with maybe some sunburn...since those leaves seem to be near the base of the plant I would assume they're older leaves, more prone to damage than newer younger leaves...if the majority of the plant looks healthy and it's only those few leaves at the bottom I wouldn't worry about it too much...maybe remove the damaged leaves if you can't stand looking at them... Also, try to cut town on the amount of sun the plant is getting...

If most of the leaves on the plant look like the pictures you posted then there is an issue, but it's beyond my expertise...maybe others here will have some ideas...

I am not at all sure, but I think those spots may be sunburn. Leaves overall being lightly colored confirms that the plant lived in strong light. It's not life-threatening.

Yes looks damaged to me by something or possible sunburn. Can I recommend with soil plus perlite. The soil looks as if it needs perlite. Otherwise it will die from drainage issues. I use 50% soil and 50% perlite.