I'd say COVID had more to do with it, but whatever.

If you like. Either way, it's not the result of Biden's Administration failing to enforce, but because of other factors that made it all-but-impossible for U.S. exporters to actually take advantage of that two-year window. Whether because of the damage inflicted to U.S. exporters over the previous two years of the trade war, the unexpected occurrence of COVID, or the poorly structured deal that only resulted in a two year commitment in the first place: the seeds of failure were planted long before Biden was elected.

The broader point still stands - we were doing nothing to lessen our dependence on China for critical things.

Do you not recall the CHIPS Act? The local preference requirements of the Inflation Reduction Act that were interwoven into that industrial policy? There are smart ways to go about a targeted lessening of dependence on China for critical things - including but not limited to broadening our import sources to other low-cost producers to diversify our sourcing. Here's an idea: we could enter into trade agreements and mutually beneficial open-market trading arrangements with other counties in Southeast Asia that would both diversity our sourcing and help check Chinese regional hegemony. We could call it a trans-Pacific partnership, for example. Or we could use industrial policy to encourage domestic production of critical industries regardless of whether that's the free market outcome - although that would involve the government "picking winners and losers."