The primary issue with Aquinas is that he’s essentially pairing a “god of the gaps” fallacy with philosophical ideas that predate the scientific method we would need in order to functionally claim most of what he’s talking about.
For example, he declares with confidence in his fourth way that because somethings are hotter, colder, etc. that there must also be an ultimate good just like there is ultimate heat. He begins the claim with scientific observation and then immediately rolls it into the field of philosophy and ethics. Now someone from the year 500AD might not consider that an issue since the scientific method didn’t even exist at the time and all natural philosophy was on the same playing field, but modern people wouldn’t consider those two fields to just be overlapping and logically interchangeable in that manner.
In the fifth way he claims that because certain beings have agency (or sapience, like us) and certain objects do not, that all non sapient objects must operate according to a being with said agency. This is patently untrue with modern scientific understanding as well, water flows because of friction and gravity, not because it was caused to do so by a god of some variety. Rocks fall, seasons change, etc. all due to natural processes. Not because there NEEDS to be a being with knowledge that guides it.
It’s interesting because this claim is foundless as he hasn’t proven that all objects operate based on a “plan” of some variety, he merely makes the claim that a plan from a sapient being is required for anything to happen and then begins to assess conclusions based on said claim. Moreso than that, it occurs in contradiction with his attempted understanding at potential and kinetic energy from the first way. He seems to have an idea about potential energy but then throws it out to just claim that objects or animals without knowledge operate on something else’s will.
Thus beginning a long standing religious tradition of using scientific rhetoric where its helpful and attempting to shoehorn philosophy in where it contradicts or fails to uphold.