Take a look at RAM and CPU usage. Those VMs are extremely useful but have limits: swapspace is almost mandatory, lightweight custom images like debian recommendable, and CPU load should be kept low.
On the last point consider that you have just 1/8 of oCPU guaranteed, indeed the VM has two CPUs but these are for short time bursts. If CPU time is abused the hypervisor will severely throttle the instance possibly locking it (keyword: steal time).
With proper configuration there shouldn't be any problems with running reverse proxies. I have caddy running on arch and SWAG running on debian on those VMs alongside with many other containers without issues.
Zotero is selfhostable, isn't it?