Barely one second in and we see the issue already.

When it says God is ONE, the Hebrew word for one is the word "echad". Remember when Genesis 2 tells you a man and his wife shall be ONE flesh? Two people one flesh? Same word "echad". So the idea is God is a composite One. So this is not inconsistent with the trinity.

Even Non-Christian Jewish scholars like Benjamin Sommer, Peter Schafer and Alex Seagal take it as an established fact that there is some sort of plurality within the God of the Old Testament, otherwise certain passages like for instance "let US make man in OUR image" would make no sense.

For more instances of the trinity in the Old Testament, you can see the below:

https://ab-melchizedek.medium.com/the-trinity-was-invented-centuries-after-christianity-a-rebuttal-from-the-old-and-new-testament-1d53d8c12df5