Why has Pep Guardiola started making double substitutions at half-time?

Pep Guardiola is sometimes criticised for his reluctance to make personnel changes but he has altered his approach in the past two games

Why has Pep Guardiola started making double substitutions at half-time?
Pep Guardiola is sometimes criticised for his reluctance to make personnel changes but he has altered his approach in the past two games