Search engine optimisation

What are the main changes in SEO for the last few years? At some point, I've been deeply into the industry but gave it up after a huge investment in a project that simply died during the coronavirus so I am thinking of getting back to SEO. I know that it is a fast-developing industry so all the knowledge that I have is definitely outdated, also, I know that after the latest major Google update it is much harder to promote websites. And I want you to help me decide if it is a worthy move to get back.