The U.K. has signed too many Treaties in my life so far. They seek to bind the country in for the long term. Where they succeed it offends one of our fundamental democratic principles that one Parliament cannot bind a successor. If a government signs up to a Treaty obligation which the Opposition disagrees with then it is particularly offensive as the incoming Government will find it difficult to disengage. I and my friends had two wins when both main parties wanted to sign the Maastricht Treaty. To secure it through Parliament the government had to gain the opt out from the single currency, the main point of the Treaty. It also secured an exit clause from the EU as a whole, which transformed our options and outlook.
Other Treaties do not offer such good opt outs or fail to include an exit clause. They become ways of freezing policy on an issue to the global consensus at the time of their making which may prove wrong or damaging. I do not think it would be a good idea to sign a binding Treaty designed by the World Health Organisation based on the current level of pandemic knowledge. We should learn from their data and experience and incorporate their best ideas in our future health management but not bind ourselves in.
All Treaties are in practice subject to revision or termination if all the signatories come to agree they are outdated or wrong. Some Treaties are necessary to settle a peace. These should not be disrupted by a losing combatant when they get stronger, but may need UN or other external guarantors. Treaties about everything from the environment to health usually go too far in crimping democracy. Sign too many and swathes of self government are constrained or prevented, or a future government has to exit them or amend unilaterally how to interpret them.