In the chart, the IRR from infection is 2.02, 95% CI 1.13-3.61. The IRR for 3rd dose Pfizer is 7.6, 95% CI 1.92-30.15.
Because the confidence interval of the Pfizer 3rd dose contains the datapoint for infection, there is a pretty good chance that the 3rd dose is not anymore likely to lead to myocarditis than COVID, and the result isn't statistically significant at p<=0.05. We can't say for sure.