I'm aware of a few examples, in France, Portugal & Austria.
In 2004, in France, Pentecost Monday was removed as a public holiday and replaced from 2005 with 'La journée de solidarité' - 'Solidarity Day', where workers attend work as usual, but work for free. Their wages go instead to a fund to be spent on the elderly and disabled. This decision was taken in response to the 2003 heatwave, which killed almost 15,000 elderly people in France. In 2008, the reference to Pentecost Monday was removed from the law, and Solidarity Day can now be taken on any public holiday throughout the year, although many employees still observe it on that day.
In 2012, Portugal's coalition government between PSD and CDS-PP, led by Pedro Passos Coelho, scrapped four public holidays. These were two religious; All Saints' Day (Nov 1st) and Corpus Christi (variable), and two civil; Republic Day (Oct 5th) and Restoration of Independence Day (Dec 1st). This was fairly unpopular, and came as part of a package of measures designed to increase productivity in the context of the Portuguese financial crisis.
The holidays were planned to be suspended for five years, but were restored in January 2016 under the leadership of António Costa.
Finally, in 2019, the European Court of Justice ruled that Austria's practice of granting only members of certain churches a public holiday on Good Friday was discriminatory. As a result, Good Friday was scrapped as a federal public holiday altogether, and replaced with the ability for all employees to unilaterally choose a date to take one of their personal holiday days at any point during the year - as opposed to having to obtain their employers' permission (§7a. Arbeitsruhegesetz).