Hot start problem

When it gets warm, does the starter still crank the engine over fast enough to start?
Is there any check engine light on or flashing at any time?

No lights where? On the instrument cluster, headlights, etc?
Do you have a voltmeter in order to check the battery voltage?

Okay, you meant no check engine lights on.
You can use the lights on the car as sort of a voltmeter or better yet explained like a twelve volt test light. Turn on the headlights and also open the drivers door or turn on the dome light with the light switch because I want you to watch the dome light as you turn the key to start.
First of all the dome light should be bright, if not, let me know but one of four things should happen.
1. The dome light stay bright, in other words no change and the starter not crank the engine over. That means the starter itself is not receiving any voltage at all. That could be a blown fuse, faulty starter relay, faulty neutral safety switch, bad ignition switch, etc, but I do not think it is going to do this.
2. The dome light go off completely and the starter may click just once or not at all. This usually means a loose main battery cable connection or ground loose.
3. The dome light dim heavy, almost out but still on very dim and the starter crank slow or even stop cranking and a clicking sound. This usually means either a drained battery, bad starter maybe worn bushings in the starter causing the armature to drag on the pole shoes. I think this may be it, since when it gets hot it cranks slower.
4. The dome light dim slightly and the starter crank over fast. This is normal.

Sounds like the battery is weak. I would charge it then have it load tested. Just about any auto-parts store will load test that battery for free. Or you could purchase a load tester and test the battery yourself. I bought this one from harbor freight for $21.99 and it works just fine.
https://www.harborfreight.com/100-amp-612v-battery-load-tester-61747.html

You are welcome.