Malware attacks on Linux OS is up 35%, and primarily on IoTs with the objective of using them for DDoS attacks, cryptocurrency mining, or spam email campaigns. The attacks also include the IoTs to act as command and control servers, as relays, and as entry points into corporate networks.

A Crowdstrike report looking into the attack data from 2021 summarizes the following:

In 2021, there was a 35% rise in malware targeting Linux systems compared to 2020.
XorDDoS, Mirai, and Mozi were the most prevalent families, accounting for 22% of all Linux-targeting malware attacks observed in 2021.
Mozi, in particular, had explosive growth in its activity, with ten times more samples circulating in the wild the year that passed compared to the previous one.
XorDDoS also had a notable year-over-year increase of 123%.

[bleepingcomputer.com...]

I'd like to think that there's more investment in making these IoTs more robust, but, i guess there's not a great deal of interest in that from the manufactures as it'll require investment and increase the cost of the equipment.