On the other hand, I'm also sending email for a client through AWS SES, and those emails are regularly blocked due to their IPs being on a blocklist. And indeed I also get spam delivered through AWS SES. I understand that it is a cat & mouse game for mail service providers to prevent spam being sent through their services. My point: switching to cloud providers doesn't magically solve your mail problems.
Aonther issue with large mail account providers (gmail at least), is that they will accept & deliver your message, but just "deliver" it to the spam folder. It's so annoying if mail is accepted but you don't know if it is actually seen by the recipient. This erodes trust in email. I understand mail servers don't want to tell spammers whether their email is accepted/rejected, but I would prefer a few more spams in my inbox if I at least won't miss emails.