The shortage isn't that much a result from the pandemic and people doing more DIY-projects, but because the US and China (and also Germany, if we talk about local wood) are building a lot of houses. China buys more wood from Germany now that Russia has set an export ban on wood. The only odd thing which I see is that the export ban is supposed to start in January 2022 [1] so I don't understand why China is already starting to buy more wood from Germany.
Those DIY projects, increase in home improvement, and increase in housing demand has been due to the changes in people's consumption patterns because of changes in people's work patterns due to the pandemic.
[1] https://www.margulesgroome.com/publications/russias-proposed...