Disable Javascript and CSS and see your website, if you can read and navigate around it, it should be fine then. Those checking site web are service-based, any website will have issue for them, how else they can get you to subscribe their service.
There are a lot of factors when it comes to your website speed. You can’t depend on any “speed test” on your result, even Google. Those are for references, it’s not the end result of your website performance itself. Relax…
All page builder will get some extra CSS or DIV just in case. So if you’re using one, deal with it. Complaint to one page builder doesn’t make another not the same.
This is a good plugin, it should be used on your own site. WordPress undeniably memory hogging and waste of space when it comes to media or even database if you will. But the overall eco-system just don’t allow you to play with whatever default WordPress has, such as media sizes or even the cronjob. Unless it’s your own site and you know what you’re doing.
Yes, in short, WordPress are getting more and more complex and complicated for beginner. No, Gutenberg editor is not helping yet.
If you’re using SiteGround Security plugin, delete it and change another security plugin. Very slow in term of updating in dashboard, very slow.
Not sure if the statistic is believable. But my opinion is: 1, the economy is fully opened, there is really no urgency on having a website up and keep running it, go out meet your clients. This is the least worry though. 2, too many WYSIWYG services available, WordPress has not done good job on Gutenberg editor yet. 3, pricing is too high in wordpress.com (without a WYSIWYG editor to that) for beginner.
Yes, put the WEBP on hold. There is no need for the rush, I don’t see how these WEBM or WEBP is stable yet. Wait it out until everyone is ready. There are too many issue on WEBP plugins as well, if you have such plugin, disable it.