I think it depends on how big your server capacity is. Most websites on the internet are run by renting servers. Only a few companies, like Meta, Google, have their own server to host. If a server can handle a lot of traffic, it should not have any problem handling those DDoS attacks. For example, have you ever heard that Facebook or Instagram, or Google are under a DDoS attack? Probably not.
I think I have witnessed a couple of Facebook (meta apps) outages that were attributed to DDoS attacks, so not system or service is 100% immune to such attacks. What the likes of Cloudflare help with is to reduce or mitigate on widespread attacks once they happen.
I think it all comes to how powerful or determined the attacker is. Some don't seem to give up so quickly.
These difficulties must be due to a recent outage on Google Cloud, at least in South America it happened this week. I don't remember the day. So these instabilities on the site could be DDoS but they could also be difficulties with the providers, in this case Google Cloud.