The first hit on Bing is a scholarly work that agrees with Aquinas’s, Leibniz, et all, that infinite regressions are not possible:
https://philpapers.org/archive/COHTMB.pdf
Perhaps you mean that Aquinas contradicted himself by holding beliefs in both of:
- the impossibility of an infinite regression
- that God is infinite
If so, I would agree - infinity is impossible so God cannot be infinite. The bible says God is infinite - without any justification - and Aquinas ties himself in a logical knot trying to justify that claim. Aquinas’s justification for God being infinite is given as:
1. Matter is made finite by form. Form is made finite by matter.
2. Matter is first potential to many forms, but when it receives a form it is made finite by that form.
3. Form is common to many, but when it is received by a particular matter it is then made finite.
4. Infinite matter, before it is made finite by form, is imperfect because matter without form is formless matter.
5. Form is contracted, and not made perfect, by matter. Form is infinite when not contracted by matter and thus has the nature of something perfect.
6. Being is the most formal of all things.
7. God is a divine being not received in anything, but is his own subsistent being. Therefore, God is infinite and perfect.
On [1] matter cannot exist without form so it is not made finite by form, it is finite period.
On [4] no justification for the existence of infinite formless matter is given
On [5] an infinite form is only possible in mathematics, not in reality
On [7] infinity is by definition unmeasurable, but any being can always measure itself - it is basic self awareness, so 'being' and 'infinite' are incompatible.