Although it is well-known that pptp is not secure and is subject to many forms of attacks, the reality is that a lot of legacy and embedded devices use pptp. I argue that if it is being used for routing or remote access or over an already secure connection (eg. another VPN like ikev2) then this is still acceptable. Or in a LANor in a public environment where no private data is exchanged. However, if the nature of the data is extremely sensitive, you should do whatever........

If you are using a hypervisor to test Proxmox (eg. Vbox) then changing the video card/display adapter can fix it. For example VboxSVGA causes the issue but switching to VMSVGA fixes it. For example VboxSVGA causes the issue but switching to VMSVGA fixes it. ........