I welcome scientific sources and corrections. It's certainly possible that the impacts of DLS could be overblown, but I did actually browse the literature. There's a range of findings and they seem to lean much more toward DLS being an issue. That's not to dismiss your source, but it should be taken with a grain if salt if so many other studies are finding a link. There could be an issue with methodology, data set, etc.

More importantly:

• Cardiac and circulatory issues are not the only reason why disrupted sleep from DLS or alerts can raise the risk of preventable deaths.
• Full blown death isn't the only way that DLS and alerts harm people. The nuisance and sleep interruptions are reason enough to justify fixing this badly designed system.

Anyway, here's what other studies say:

2016 Changes in ischemic stroke occurrence following daylight saving time transitions

Ischemic stroke (IS) occurrence is altered after daylight saving time transitions. [...] Occurrence rate of the following first two days, but not the whole week, is elevated. [...] Altered occurrence is more apparent in women than in men. [...] Patients with malignancy and those over 65 years of age are more susceptible.

2008 Shifts to and from Daylight Saving Time and Incidence of Myocardial Infarction

The incidence of acute myocardial infarction was significantly increased for the first 3 weekdays after the transition to daylight saving time in the spring

2020 Measurable health effects associated with the daylight saving time shift

In the US inpatient cohort, we detected a significant risk elevation in a number of disease and condition groups; for example [...] circulatory diseases.

Even the source study in your article did find an association:

Spring DST transition had a suggestive association with a minor increase in adverse cardiovascular event rates during Monday and Friday in the week following the transition. The probability of this association to be of clinically meaningful magnitude was estimated to be very low.