IR-blasting 455 kHz with the new upstream kernel modules gpio-ir-tx and pwm-ir-tx

Dear colleagues

My appliance (a heater) stopped responding reliably to sent IR signals after upgrading the Raspberry Pi 3 to raspbian 4.19.42. I tried both new kernel modules: gpio-ir-tx and pwm-ir-tx (new kernel modules from upstream for software and hardware Pulse Width Modulation PWM). Very occasionally, maybe once in a hundred, the heater picks the IR signal up. Prior to the upgrade, the system worked nicely; as the IR signal has a high carrier frequency (455 kHz) I had used a lirc-rpi module that I had modified for hardware PWM. I measured the signal at the GPIO pin with a picoscope and noted that the carrier frequency was a bit too high when using pwm-ir-tx (around 475 - 480 kHz) and much too low when using gpio-ir-tx.

Could this be a reason for my IR signal to fail? Does anyone have experience with IR blasting at a high carrier frequency (455 kHz) using gpio-ir-tx or pwm-ir-tx?

Thanks for sharing any experience that you may have.

Andreas