id be careful pumping fake visits just for the report, if the client ever looks at leads next to the traffic line it falls apart fast, and junk sessions in ga4 are pretty easy to spot, zero engagement, weird geo, all hitting the same landing page.
first thing id do is check gsc for what actually dropped, which queries and which pages, and whether its a ranking drop or just impressions and seasonality. a lot of these 2 month slides are one update hitting a couple of pages.
quick wins that show up honestly: rewrite titles and metas on pages sitting at 5-15 with low ctr, add internal links to the pages that dropped, and fix anything that fell out of the index. if you do test ctr, put it on those page 1-2 terms to actually move rankings, not just to pad sessions.